1. Field of the Invention
This invention is directed to fatliquoring or more particularly to leather fatting agents. This invention is particularly directed to leather fatty agents derived from free-flowing dried pulverulent products. This invention is also directed to a process for fatting a leather with a solution, emulsion or dispersion of an initially free-flowing pulverulent product derived from a liquid or paste, especially one based upon a fatty, oily or waxy substance.
2. Discussion of the Prior Art
During the treatment of leather it is common to treat the same with a chrome tanning agent. For some time after the operation of the chrome tanning, while the tan is developing, there is a slow development of acidity in the leather. Thus, after splitting and levelling, the leather is washed or treated with sodium bicarbonate, borax or some other mild alkali to remove the free acid. It has been found that the fibers of the leather can be lubricated by fatliquoring process so as to impart to the leather good strength and flexibility. In the fatliquoring operation the oils and fats employed are added to the leather in an emulsion, solution or dispersion form, preferably as an aqueous emulsion. According to theory, fatliquoring is a method of incorporating oil or fat into the leather by means of an aqueous suspension of oil or fat which remains stable at the pH of the neutralized leather. As leather is usually neutralized only on the grain and flesh surfaces and to a slight depth beneath these surfaces, the fatliquor is designed to penetrate to the depth of the effect of the neutralizing agent.
For some time now it has been known to employ numerous types of animal oils, mineral oils and vegetable oils in the fatliquoring operation. The fatliquor solutions are made up of a mixture of raw oil and a soap or sulfated oil. The soap or sulfated oil serves as a carrier for the raw oil and an emulsion is formed when the two are mixed with water in proper form so that the fatliquor is readily absorbed by the leather.
The neutralized leather is placed in a drum and may be both dyed and fatliquored in one continuous operation, or dyed first and then fatliquored. A sulfated oil--raw oil mixture is used, suitably employing between 1 and 3% of oil based on the stock wet wrung weight. The amount of water employed varies; the weight ratio of emulsion to stock may vary from 1:1 to 3:1. The leather is usually fatliquored for thirty minutes to one hour while drumming at 120.degree. F. After fatliquoring, the stock is piled up over night and then set out to dry by various methods, such as paste drying or toggling.
It, therefore, has become desirable to provide improved fatliquoring or leather fatting substances which would penetrate deeply into the interior of the leather. Moreover, it has become desirable to provide a solid product which can be readily made into an aqueous emulsion form to be used as leather fatting agent. It has become desirably, additionally, to provide a material useful as a leather fatting agent which is readily absorbed from the solution, emulsion or dispersion and enters within the pores of the leather so treated. Still moreover, it has become desirable to provide a leather fatting solution, emulsion or dispersion in which an exceptionally high percentage of leather fatting agent contained therein is absorbed by the leather.